From WO 2005/037553 A1 a printing unit of a printing press is known, wherein the printing unit is embodied as a printing tower and wherein at least two frame parts are provided, the relative distance between which can be modified. One of the frame parts is embodied as stationary and the other of the frame parts is embodied as movable. The movable frame part can be moved to a position in which it is spaced from the stationary frame part, creating an intermediate space between the frame parts and therefore also between the blanket cylinders of the two frame parts, wherein a press operator can enter the intermediate space and perform maintenance operations such as replacing the blanket. When the printing unit is in this opened position, the imprinted paper web, or the paper web to be imprinted, rests against the blanket cylinders of the stationary frame part. Once the maintenance operation is completed, the movable frame part is moved back up to the stationary frame part.
From DE 195 48 819 A1 a printing unit is known, which is embodied as a printing tower. One of the printing couples of said printing unit can be in print operation while another printing couple of the printing unit is in the print-off position. In the print-off position, a print-off gap is formed between the blanket cylinders. The printing unit has a plurality of displacement devices, one or more of which are placed against the paper web so as to allow the paper web to pass through the printing couple that is in the print-off position without coming into contact with the blanket cylinders. The displacement devices are embodied as ink-repellent paper guiding rollers that can be moved back and forth.
From DE 10 2004 009 861 A1 a method and a device for operating printing units is known. The printing units have movable web guiding elements with which the paper web can be guided through the print-off gap between two blanket cylinders of a printing couple that is in the print-off position, without coming into contact with said cylinders. These web guiding elements can be positioned in the infeed area and/or in the outfeed area of a printing couple. If one web guiding element is arranged in the infeed area and another web guiding element is arranged in the outfeed area of the printing couple, at least the web guiding element located in the outfeed area is embodied as movable. The movable web guiding element is positioned by means of drives, wherein the drives are preferably remotely actuated via a control device. The drives can be embodied as pressure-actuated cylinders or as electric motors.
DE 44 08 025 A1 discloses a printing unit with two frame parts, the distance between which can be modified. Guiding rollers are provided for guiding the web.